Effects of repeated cycles of sterilisation on the mechanical characteristics of titanium miniplates for osteosynthesis.

AIM

This study investigates the changes occurring in the mechanical characteristics of osteosynthesis titanium miniplates when exposed to repeated sterilization cycles.

METHODS

For this study Medicon (c) titanium miniplates were used. The characteristics of miniplates were evaluated using the Penetration Resistance test, MSC/Pal2 Software, and the Finite Elements Method (F.E.M.). Surface roughness measurements were also carried out. Statistical analysis was conducted using the One way ANOVA model. The significance level was set at >0.05.

RESULTS

The one way ANOVA analysis between HV value and increased sterilization cycles showed P>0.029; between the Ra value and increased sterilization cycles it was P>0.325; between the Rq value and increased sterilization cycles it was P>0.703. The Finite Element Model shows an amplified deformed shape of the miniplate at a load of 196 [N]. At this load value the equivalent 'von Mises stress' reaches the value of sigmaP0.2, shown by the ASTM F 67-95 standard. Stress distribution comparison between the six-holed plate and the equivalent straight miniplate shows more consistent behaviour for the Medicon (c) miniplate. The rigidity of the Medicon (c) miniplate is 14.46, lower than that for the equivalent straight miniplate (R=23.4). The ANOVA analysis between the break load and increased sterilization cycles showed P>0.175; between the break position and increased sterilization cycles it showed P>0.016.

CONCLUSIONS

Experimental static tests have shown that all tested miniplates did not have notable differences and this suggests that sterilization cycles do not affect mechanical characteristics.